U.S. Pat. No. 6,635,960 in the name of Farrar Oct. 21, 2003 teaches that the chips would be positioned at the desired angle prior to attaching the first connecting member to the second connecting member; Flip chip technology is well known, for example the process is described in U.S. Pat. No. 6,053,395 in the name of Sasaki, and in United States Patent. U.S. Pat. No. 5,963,793 in the names of Rinne and Deane, the applicant of this application, describes a flip-chip solder bump technique for where after reflow, a solder bump which extends across a pair of adjacent substrates forms an arched solder column or partial ring of solder between the two substrates. This allows one substrate to be soldered to another with an oblique angle therebetween.
In edge emitting laser diode systems, a monitor photodiode is used in a feedback loop to control the laser chip's power output. The photodiode's active surface must be pointed toward the laser chip's backside facet. The angle between the photodiode's active surface and the incident laser beam from the laser chip does not need to be 90 degrees; angles between 30 and 60 degrees are acceptable.
Power monitoring photodiodes used in edge emitting pump and source lasers are often assembled in a manner to receive an optical beam and convert the optical signal into an electrical one. Typically, the photodiode is mounted to a submount that is then joined to a substrate that includes the edge emitting laser chip. The submount is assembled to the substrate such that the photodiode is perpendicular to the light path from the laser chip (FIG. 1).
It is known to mount elements on a substrate using solder bumping or solder printing. Flip-chip technology is also well known in the art. Generally, flip-chip technology involves chips with numerous solder bump interconnection terminals. After solder joining the chip to a substrate, the arrangement of solder bumps results in the chip being oriented substantially parallel to the substrate, assuming that all the bumps are of substantially equal size. U.S. Pat. No. 6,418,033 in the name of Rinne assigned to Unitive Electronics, Inc., incorporated herein by reference discloses mounting a plurality of substrates on solder bumps mounted to a first microelectronic substrate as a means of increasing packing density. Customarily in the art, when two circuit boards are to be physically connected to one another with a predetermined angle therebetween, it can be achieved between by heating the solder bumps so as to cause it them reflow while holding the element with respect to the substrate at a predetermined desired angle during the reflow process. The melted solder bumps form the “glue” and electrical contact if it is so required, and when the solder cools and solidifies, the element that was held in place at a desired angle, is fixed at that angle. If there are just two solder bumps or if the bumps are arranged in a line, the chip resting upon them would be unstable during the solder joining process and it would tend to tilt to one side or the other. This behaviour is the basis of the present invention.
It would be desirable to provide a controllable method of assembling one or many small electronic elements such as photodiodes at a predetermined angle to the substrate, using soldering or an equivalent approach. The angle is measured between the main surface of the substrate and the major surface of the element or elements.
It would be desirable to provide a controllable method of assembling one or many small circuit boards to the substrate, using soldering or an equivalent approach. The angle is measured between the main surface of the substrate and the major surface of the circuit board or boards.